COM registration methods should be matched

A type declares a method marked with the System.Runtime.InteropServices.ComRegisterFunctionAttribute attribute but does not declare a method marked with the System.Runtime.InteropServices.ComUnregisterFunctionAttribute attribute, or vice versa.

For COM clients to create a .NET Framework type, the type must first be registered. If it is available, a method marked with the ComRegisterFunctionAttribute attribute is called during the registration process to run user specified code. A corresponding method marked with the ComUnregisterFunctionAttribute attribute is called during the unregistration process to reverse the operations of the registration method.

To fix a violation of this rule add the corresponding registration or unregistration method.

Do not suppress a warning from this rule.

The following example shows a type that violates the rule. The commented code shows the fix for the violation.

using System;
using System.Runtime.InteropServices;

[assembly: ComVisible(true)]
namespace InteroperabilityLibrary
{
   public class ClassToRegister
   {
   }

   public class ComRegistration
   {
      [ComRegisterFunction]
      internal static void RegisterFunction(Type typeToRegister) {}

//      [ComUnregisterFunction] 
//      internal static void UnregisterFunction(Type typeToRegister) {}
   }
}

COM registration methods should not be visible

Concepts

Reference